Need help choosing a new graphics card

I'm looking to buy myself a new graphics card which will allow me to run GW2 on max settings ideally. My main concern is with WvWvW. When part of large battles, my frame rate decreases almost to a standstill. I even have some issues with PvE and that's with most settings set to low/medium.

I would appreciate any suggestions for graphics cards in the £100-150 range that can at least run everything on medium, regardless of whats happening on the screen.

The FX series of processors is not as good as the i5 series, but the FX-4170 is one of the fastest FX, other than the newer FX-8320/8350. So, the CPU is not your whole problem - although even after a GPU upgrade, you'll still take a big fps hit in WvW.
To really boost CPU performance would require a CPU + motherboard upgrade.

Your main problem at this point is your GPU. The HD6670 is the bare minimum you'd want to try gaming with. Unfortunately, you didn't tell us what the wattage of your power supply is - which matters a lot when choosing a GPU.

If you have a 500watt power supply you could, in your price range, look at a GTX 650 Ti or HD7850. Ideally you'd want a GTX-660 Ti or HD7870, but they cost a bit more.

If your power supply is only 300-350 watts you'd be limited to an HD7750, which isn't that much of an upgrade over the 6670. If it's 400watts or so, you could use an HD7770.

Thank you for the detailed answer Quaker. I have a 500W power supply, so i think I'll take a look at the cards that you suggested for that range. I very much doubted that my CPU was an issue here as its quad core with quite a high ghz value.

I very much doubted that my CPU was an issue here as its quad core with quite a high ghz value.

There's an awful lot more to it than that. There isn't really any single number you can compare. Chip architecture and instructions-per-clock are often what really sets processors apart, and those are things AMD tends to struggle with. Your FX-4170 is respectable, but its causing you to drop significantly in CPU-heavy situations in GW2 (relative to faster chips, anyway) even if its GHz clock speed looks high on paper. I agree that a video card upgrade is easier and more worthwhile for you at this point, though.

The different aftermarket brands of the GTX 660 Ti are essentially the same chips attached to slightly different boards with different coolers. Any would work, but often the warranties and support differ. I see Asus, MSI, EVGA and Gigabyte in that list, those are all excellent choices. I don't know Palit, Gainward and PNY as well.

Thank you for the detailed answer Quaker. I have a 500W power supply, so i think I'll take a look at the cards that you suggested for that range. I very much doubted that my CPU was an issue here as its quad core with quite a high ghz value.

TO AMAZON!

What brand of PSU is it? It might say it's 500W but if it's a cheap PSU it wont deliver anywhere near that.

I just paid a visit to Amazon and there is a whole selection of GTX-660 TI GPU's. They all seem to look different so will I have to pick the right one according to my CPU?

No, it doesn't matter what the CPU is. But get a good brand as Typo suggested.

And speaking of CPUs - technically, the FX-4170 is not a "quad-core". It has two "processor modules" which each contain two semi-CPUs that share many resources. Performance-wise, it is somewhere between two Intel cores with HyperThreading and 4 true cores. Picky, picky.

And, speaking of PSUs - the PSU requirements as given by the manufacturer already have a lot of headroom in them to allow for the varying quality of PSUs and the varying power requirements of the CPU, mobo, drives, etc. So unless your power supply is absolute crap, it should be fine.